* If you didn't use FastAPI and used Starlette directly (or another tool, like Sanic, Flask, Responder, etc) you would have to implement all the data validation and serialization yourself. So, your final application would still have...

  // Required.
  optional MatchResources matchConstraints = 2;

  // Validations contain CEL expressions which is used to apply the validation.
  // Validations and AuditAnnotations may not both be empty; a minimum of one Validations or AuditAnnotations is
  // required.
  // +listType=atomic
  // +optional
  repeated Validation validations = 3;

Another big feature needed by APIs is data validation, making sure that the data is valid, given certain parameters. For example, that some field is an `int`, and not some random string. This is especially useful for incoming data.

Without a data validation system, you would have to do all the checks by hand, in code.

Mais, **tout fonctionne** par défaut.

### Validation

* Validation pour la plupart (ou tous?) les **types de données** Python incluant:
    * objets JSON (`dict`).
    * listes JSON (`list`) définissant des types d'éléments.
    * Champs String (`str`), définition de longueur minimum ou maximale.
    * Nombres (`int`, `float`) avec valeur minimale and maximale, etc.

* Validation pour des types plus exotiques, tel que:
    * URL.

But by default, it all **"just works"**.

### Validation

* Validation for most (or all?) Python **data types**, including:
    * JSON objects (`dict`).
    * JSON array (`list`) defining item types.
    * String (`str`) fields, defining min and max lengths.
    * Numbers (`int`, `float`) with min and max values, etc.

* Validation for more exotic types, like:
    * URL.
    * Email.
    * UUID.

        - ""
        - -b
        - '*'
        - -d
        - 15090,15021,15020
        - --log_output_level=default:info
        - --run-validation
        - --skip-rule-apply
        image: gcr.io/istio-testing/proxyv2:latest
        name: istio-validation
        resources:
          limits:
            cpu: "2"
            memory: 1Gi
          requests:
            cpu: 100m

Nhưng mặc định, tất cả **đều hoạt động**.

### Validation

* Validation cho đa số (hoặc tất cả?) **các kiểu dữ liệu** Python, bao gồm:
    * JSON objects (`dict`).
    * Mảng JSON (`list`) định nghĩa kiểu dữ liệu từng phần tử.
    * Xâu (`str`), định nghĩa độ dài lớn nhất, nhỏ nhất.
    * Số (`int`, `float`) với các giá trị lớn nhất, nhỏ nhất, etc.

* Validation cho nhiều kiểu dữ liệu bên ngoài như:
    * URL.

!!! check "vérifier"
    Donc, avec ces mêmes déclarations de type Python, **FastAPI** vous fournit de la validation de données.

    Notez que l'erreur mentionne le point exact où la validation n'a pas réussi.

    Ce qui est incroyablement utile au moment de développer et débugger du code qui interagit avec votre API.

## Documentation

# `Request` class

You can declare a parameter in a *path operation function* or dependency to be of type `Request` and then you can access the raw request object directly, without any validation, etc.

You can import it directly from `fastapi`:

```python
from fastapi import Request
```

!!! tip

  @get:JvmName("noCache") val noCache: Boolean,
  /** If true, this response should not be cached. */
  @get:JvmName("noStore") val noStore: Boolean,
  /** The duration past the response's served date that it can be served without validation. */
  @get:JvmName("maxAgeSeconds") val maxAgeSeconds: Int,
  /**
   * The "s-maxage" directive is the max age for shared caches. Not to be confused with "max-age"